Semiconductor devices, whether single component architectures or multi-component semiconductor integrated circuits (ICs), hereinafter generically referred to as ICs, are typically formed in arrays containing large numbers of copies of the devices on a semiconductor wafer. Semiconductor wafers, may by way of example, be formed from Si, GaAs, or GaN. After formation of the ICs, the wafer is separated, “diced”, into pieces referred to as “dies”, each of which comprises a single copy of an IC formed on the wafer. Components of the IC, such as sources, drains, and gates of transistors, comprised in the die that require electrical connection to external circuitry with which the IC is to operate are electrically connected to conductive contact pads, also referred to as die pads, that are formed on a surface of the die. The dies are typically mounted to a submount and together with the submount are encapsulated in a “die package” by potting or molding in a protective epoxy or plastic. The submount mechanically supports the die and electrically conductive package leads or solder-bumps that extend from the package or are otherwise readily accessible from outside the die package. The die package leads or solder bumps are used to electrically connect the “packaged die” to an external circuit with which the die is to be used and are electrically connected to the die's contact pads by conductive bondwires. The bondwires are usually formed from copper (Cu), aluminum (Al), or gold (Au). It is noted that a die package is not limited to comprising a single die, and may contain more than one die that are optionally electrically connected to each other as well as having contact pads, solder bumps and/or package leads for connecting the package and the dies to external circuits.
Whereas dies before packaging may be referred to as “bare dies”, and packaged dies or die packages may be referred to as “chips”, conventionally the distinction between dies and chips is often blurred, and chips, dies, and die packages are often used interchangeably. Unless indicated specifically or by context, a die or bare die refers to a “bare die”, a “die package” refers to a packaged die or dies, and a “chip” refers generically to bare dies and die packages.
Devices that provide many of today's military, space, and civilian applications, such as radars, communication network elements, computers, cell phones, notebooks, and tablets, typically require electronic circuitry comprising a variety of different chips and electronic components such as passive circuit elements, conventionally referred to as “passives”, and other electronic components that provide different functionalities needed for the applications performed by the devices. Some devices may require both digital and analog functionalities and corresponding digital and analog chips. For example, cell phones require analog circuit elements for their RF front end systems as well as digital audio and video signal processors. As many of today's devices shrink in size, and/or are configured to provide larger video interfaces for their operators, space and power available for housing and powering the chips and associated circuit elements that cooperate to provide the devices' applications decreases.
Constraints generated by reduction in space and power available for device circuitry may generally be met by producing electronic circuitry having a smaller footprint. A footprint refers to an area that the circuitry occupies on a printed circuit board on which the circuitry is supported. Reducing a circuitry's footprint may be achieved by reducing the footprints of its components and/or increasing the packing density of the components. Generally, it is not possible or advantageous to provide a desired degree of reduction in a footprint of a given electronic circuitry by forming the architectures of the various chips and circuit elements in the electronic circuitry as components of a single monolithic integrated circuit. Different chip architectures may require different, non-compatible fabrication processes. In addition, it is often not practical to attempt to reproduce the reliability and performance of known operational chips that provide needed circuit functionalities as component architectures of a single monolithic integrated circuit.
In lieu of monolithic, fully integrated circuits, industry has developed multi-chip modules (MCMs) or systems in a package (SIPs), hereinafter generically referred to as MCMs, to reduce space and power requirements of many of today's devices. A MCM is an electronic system comprising a plurality of chips and/or associated electronic components that are assembled on a common substrate or a stack of shared substrates. A substrate, which may be referred to in the art as an “interposer”, may, by way of example, be a printed circuit board (PCB), or a thin or thick plate formed from a suitable material such as a ceramic, Si, GaAs, or GaN that comprises a suitable pattern of conducting traces. The chips and electronic components on the substrate or substrates are electrically connected to each other and the conducting traces using conventional techniques. The traces are designed, and the chips and components are located to reduce a foot print of the MCM assembly relative to a footprint the chips and components would have as individual elements conventionally assembled on a PCB, and so that the chips and components may share common power and thermal dissipation resources. The assembled chips and components are encapsulated in an overmolding process so that the MCM appears and functions as a single die package.